The present invention generally relates to apparatus for curing coating materials, and more particularly to apparatus for irradiating the coating on a magnet wire or wire-like element using UV and IR radiation, visible light and convective heat.
Magnet wire is single strand copper wire with a hard thin protective coating bonded to the wire. The physical properties of the baked-on coating determine the dielectric strength, thermal rating, and resistance to damage of the wire. The wire is typically used for winding transformers, motors and solenoid coils.
Magnet wire coatings are bonded to the wire by baking them in convection ovens. The finished wire consists of 15 to 30 thin coatings that are each baked on before the next layer is applied. The process is not energy efficient.
The wire is dragged through weakly pressurized dies to apply the first layer of coating. After coating, the wire passes through a long drying oven (45-55 ft) and is cooled subsequently in a long cooling tunnel. The wire must be cooled to eliminate wet-coating vaporization. The wire is then circulated back for the next of 14 to 29 coating passes. Process speeds are limited by the thermal inertia of heating the copper wire and the number of coating passes, which is determined by the coating thickness. The larger the wire, the longer the oven and cool down tunnel. Speeds drop dramatically with increases in wire size.
It is an object of the present invention to provide an apparatus for curing the coating on magnet wires or wire-like elements that obviates the disadvantages of the prior art.
It is another object of the present invention to provide an apparatus that generates UV radiation, visible radiation, infrared radiation and convective heat to cure the coating on magnet wires or wire-like elements.
In summary, the present invention provides a UV oven comprising a compact longitudinal elliptical reflector with first and second focal lines; a longitudinal small diameter bulb disposed along the first focal line that generates short wavelength UV radiation, IR radiation, visible radiation and heat to cure the coating on magnet wires or wire-like elements that are passed through the other focal line. The inside surface of the reflector is coated with material to enhance the reflectivity of the short wavelength UV, IR and visible radiation. The bulb envelope is made of quartz material that allows transmission of short wavelength UV radiation. The small diameter bulb has been found to increase the power output in the short wavelength UV range.
In another embodiment of the invention, two separate compact elliptical longitudinal reflectors are used, each provided with a bulb. The magnet wires or wire-like elements to be cured are passed along the common focal line of the reflectors, subjecting the wires to the energy output of the two bulbs.
In yet another embodiment of the invention, the magnet wires or wire-like elements are placed even closer to the bulb. A compact elliptical longitudinal reflector includes a longitudinal bulb disposed along a focal line of the reflector. A back reflector is disposed in close proximity to the bulb. The wires to be cured are passed between the bulb and the back reflector.
These and other objects of the present invention will become apparent from the following detailed description.